You are currently viewing Prove that tan^2(x) + 1 = sec^2(x)
tan^2(x) + 1 = sec^2(x)

Prove that tan^2(x) + 1 = sec^2(x)

The function \tan^2(x) + 1 is equal to \sec^2(x).

Proof. We have seen here that:
\begin{align*}
\sin^2(x) + \cos^2(x) = 1.
\end{align*}
Now multiply both sides with \frac{1}{\cos^2(x)} gives us:
\begin{align*}
\frac{\sin^2(x)}{\cos^2(x)} + 1 = \frac{1}{\cos^2(x)}.
\end{align*}
We do know that \frac{\sin^2(x)}{\cos^2(x)} = \tan^2(x) and \frac{1}{\cos^2(x)} = \sec^2(x). Therefore, we get the following:
\begin{align*}
\tan^2(x) + 1 = \sec^2(x).
\end{align*}
Therefore, \tan^2(x) + 1 is equal to \sec^2(x).

Leave a Reply